Fabric conditioning compositions, in particular fabric softening compositions to be used in the rinse cycle of laundry washing processes, are well known.
Typically, such compositions contain a water-insoluble quaternary-ammonium fabric softening agent, the most commonly used having been di-long alkyl chain ammonium chloride.
In recent years, the need has arisen for more environmentally-friendly materials, and rapidly biodegradable quaternary ammonium compounds have been presented as alternatives to the traditionaly used di-long chain ammonium chlorides. Such quaternary ammonium compounds contain long chain alk(en)yl groups interrupted by functional groups such as carboxy groups.
Said materials and fabric softening compositions containing them are disclosed in numerous publications such as EPA 040 562, and EPA 239 910, incorporated herein by reference in their entirety.
In EPA 239 910, it has been disclosed that a pH range of from 2.5 to 4.2 provides optimum storage stability to said rapidly biodegradable ammonium compounds.
On the other hand, the anti-harshening effect of cellulase on fabrics is known from e.g. FR 2 481 712 or GB-A-1 368 599, as well as their fabric care benefits, disclosed in e.g. EPA 269 168, all incorporated herein by reference in their entirety. Cellulases have been mainly described however for use in detergent compositions to be used in the main wash cycle of laundry processes, and have found some commercial application in this context. The use of cellulases in rinse added fabric softener compositions has not been pursued so far; one of the potential issues to be resolved being to provide acceptable stability of the cellulase in such compositions upon storage.
While the pH of the rinse-added fabric softening compositions in GB-A-1 368 599, as well as all compositions containing traditional fabric softener actives was typically in the range of 5 to 7, and the "pH optimum" for cellulase activity is known to be from 5 to 9.5, it has now been surprisingly discovered that when cellulases are included in fabric softening compositions of the type disclosed in EPA 239 910, i.e. with certain rapidly biodegradable ammonium compounds or their amine precursors and at a narrowly defined low pH range, the stability of said cellulases upon storage is remarkable.
The present invention therefore allows to formulate fabric conditioning compositions which are preferably storage stable, and therefore Where the full potential of both the softening actives and the cellulases, in terms of softness and fabric care benefits, is preserved.